I've seen many time ppl buy "8-core" AMD CPUs, mislead by number of cores and absolutely convinced its best bang for the money, instead of 2500K or even 3570K, which have only 4 cores. I know which is better for crunching, but recently friend of mine bought 8320 CPU and put it under the high end water cooling, so I decided to run a comparison between this 8320, my old 2500K and a 8120, which he took temporarily to compare Buldozer and Vishera core arhitectures.
We settled at 4.6 GHz frequency for testing, as his MSI mobo has some issues with Visheras and 8120 is barely able to reach higher frequency. My 2500K is perfectly OK with old Noctua NH-U12 cooler, running 4.6 GHz 24/7, crunching our favorite SETI.
Beside completion times, we measured power consumption. Values, given here, are the values from wall socket, where consumption of all components, included in all systems, except motherboard, memory and CPU are excluded. So the numbers bellow are only for those three. Also, values are raw, PSU efficiency is not applied, but both systems are equipped with high end PSU, with similar percentage load, so we can assume, efficiency is close enough for both systems. Energy used per WU is based on load consumption minus idle consumption, only difference between these two.
Also, for comparison sake, I included my shiny new 3930K, running also at 4.6 GHz. But its not part of general comparison, bcs its price is way higher. Anyways, its interesting to see out how energy efficient it is, as it is rarely seen CPU, especially here and even more especially, running at such high frequency.
Test is based on running 24 MB WU tasks with most common AR lately - 0.385, in different scenarios and target is finding average time per task, wattage per task and total number of tasks per day. There are some runs for AMD CPU with different memory settings to see how they affect crunching speed. I also decided, it is need to be seen how good AMDs wil be running only 4 tasks simultanenously, as they have 4 physical FPUs - this is where "MT efficiency" comes from - its actual gain from running 8 tasks, compared with 4 tasks. For 3930K CPU, there is "HT efficiency", standing for difference with running 12 and 6 simultaneous threads(MB tasks in our case). "Average CPU time" is time for a single task, as it is written in client_state.xml file, after completion.
Actually, tasks ran are more, 36, so to not let cores being idle, when they complete some task, but only 24, same for all runs were taken into account. Some note on Intel CPUs - they uses fastest client available, SSE3 Intel. I ran tests with all available clients from Lunatics installer and picked the fastest. I also included 3930K with only 4 cores and hyper-threading enabled, to simulate 8-threaded Sandy Bridge(well, can't ignore 4 MB more cache, but life is a bitch). For AMD CPU, best client is known, not much choices to make :) I ran also AMD SSE3 client on Intel CPUs and 3930K on 4.7 GHz(just to prove it can do it and to see scaling. It can actually do 4.9 GHz with this cooling, but VRM temperature reaches 120 degrees Celsius, which is not healthy for the system). If someone needs full data, let me know, I'll post it.
Important, those msot likely to be scenarious, are made bold for easy viewing.

Well, conclusion is obvious. 2500K is faster than Vishera(which is faster than Buldozer) and it is twice more energy efficient. Based on electricity prices here in Bulgaria, where we have relatively cheap electricity, and prices of CPU + Mobo, able to achieve such frequencies(not counting the price of water cooling for Vishera) it will take three months 24/7 cruching to make cost of ownership of Intel system same as Vishera system. In areas with more expensive energy, it will take less. Lately, things are even better for having 2500K, as Microcenter USA gave them for 99 US bucks for a piece with store pick-up, and greater availability of 2500K second hand(btw, Microcenter Minneapolis was most messy computer parts store I've ever seen - was like post-nuclear scenery :). Unusual for US, but there is was. And maybe still is, will see again this summer). There are more good thing of having 2500K, instead on 8320. 2500K overclocks better with box cooler. 4.2-4.3 is usual range. Vishera can reach 4 GHz, but you wont like temperatures - they are very close to temperatures where most AMD CPUs fail, I wouldn't leave 24/7 like this. And one more thing. Bcs of low completion times per WU with 2500K, I find it more error prone - errors can be caught more faster and less work is lost if CPU trashes units and gives errors.
I'm happy 2500K owner for two years, and above is the prove that it is good piece of hardware, worth the money. 12K RAC average(100 units*120 credits each) from CPU is descent value.
I'm even more happy with 3930K, but as we know, it is in other category. It can go further than 20K RAC per day, which I find very impressive value for CPU. THe most impressive part it the tests with it was, that it is very close as for energy efficiency to its low end counterparts, in contrary to my expectations.
I'm looking forward to replace 2500K with 3570K, which is even more faster(around 15% expected) and more energy efficient, but its only if good deal comes around.

Average CPU time for one WU - 3297.2 s
Same, but in format h:m:s - 0:54:57
1.09 WU/h - number of WU per core for one hour
26.21 WU/day per core - this is self explanatory, above, multiplied by 24 hours
104.82 WU/day per core package - number of active cores, multiplied by above number
24.04 W/WU - doesn't need explanation

Actually, I've ran this r557 AP application, but for Windows, on 3930K(4.6 GHz), with and without AVX(Win XP x64 and Win7 x64). Difference in not that big, although it is significant. 4:20 hours without AVX(can be seen in my computers page even now) vs a lil bit less than 4 hours with AVX.
AFAIK, there isnt MB application for Windows, which uses AVX. Only Astropulse. And switching to Linux is not an option :)

I don't know exactly, this CPU never ran on default frequency. But you can calculate, scaling of compeltion times is same as frequency scaling. Add some 30% to times and it will give approximate values for default 3.2 GHz(non-turbo frequency, we assume all cores are loaded) of 3930K.
Perhaps Linux apps are just better optimized.

I don't know exactly, this CPU never ran on default frequency. But you can calculate, scaling of compeltion times is same as frequency scaling. Add some 30% to times and it will give approximate values for default 3.2 GHz(non-turbo frequency, we assume all cores are loaded) of 3930K.
Perhaps Linux apps are just better optimized.

So, without the OC, the AVX, and at 3.2 GHz, the time would be a little less than 6 hours. 3.5 hours sounds so much better. Still, less than 6 hours is much better than with my 2.8 GHz Xeon running r557.

On my 2500K the old non-AVX AP app took almost 6hrs to complete @ 3.4GHz but the AVX AP app dropped that down to just over 5hrs.

Back on topic, I've made comments before in threads where people have asked AMD or Intel and I've always stated that the small amount that is saved by buying an AMD CPU setup will soon be cancelled out by the power consumption and still not produce the results that Intel produce which those figures just backup.

No I'm not an Intel fan, even though all 3 of my rigs are currently Intel but I've had plenty of AMD setups in the past, but in my books AMD has not produced a properly balanced CPU since the Athlon X2/X4 range, they just use more power without producing an equivalent higher output, in fact several models since have just gone backwards IMO.

I am using an Opteron 1210 at 1.8 GHz burning 75 W, bought in 2008, and an APU E350 at 1.6 GHz burning 18 W bought last year. Their performance is about equal, no GPU. The Opteron powers a SUN WS, the APU a HP laptop where I installed a SSD by OCZ. Both use SuSE Linux.
Tullio

When is the new lunatics cpu app available with avx extensions for sandy / ivy bridge?

All apps build with latest FFTW library (and Lunatics do) have some AVX support, at least in FFT part. Some additional AVX code was added by Joe Segur to MB stock, but still not adopted for opt builds. Maybe new stock MB will have AVX support then.SETI apps news
We're not gonna fight them. We're gonna transcend them.

It will be great, if u test with 6 and 12 enabled threads, same tasks. Interestingly, on this processor, HT efficiency is almost non-existent with AP, even worse, 12 simultaneous tasks are finished same slow as two groups of 6 tasks(I turn off HT completely from BIOS - XP scheduler get confused with more than 8 cores - if 6 tasks are being run with 12 cores enabled, it does not put one task per physical core, but uses very often two logical cores of same physical core, even when there is other free physical cores. With 4 tasks on 8 cores it does make it OK). For example, this run, from first post, with 12 simultaneous tasks, where HT efficiency is 16.5%, when I ran it second time, gave me even worse result than 2 sets of 6 tasks, something like "negative HT efficiency".

Raistmer, if your Intel OpenCL application can run on Sandy Bitch too, I'm ready to test it. You may contact me on PM with details any time.